(a) Field of the Invention
The present invention relates to an inkjet printing system and a manufacturing method of a display device using the same.
(b) Description of the Related Art
A flat panel display is a display device that is thin compared with the size of the screen thereof, and a liquid crystal display (“LCD”) and an organic light emitting device (“OLED”) are among the most widely used flat panel displays.
As one of the most widely used flat panel displays, a liquid crystal display (“LCD”) includes two display panels with a liquid crystal layer interposed therebetween, and a plurality of color filters for displaying colors. In the two display panels, electric field generating electrodes such as a pixel electrode and a common electrode, and an alignment film are formed. The alignment layer determines initial alignment of liquid crystal molecules, and the electric field generating electrodes change alignment of the liquid crystal molecules of the liquid crystal layer by generating an electric field therebetween. In such an LCD, incident light passing through the liquid crystal layer has a polarization state that varies according to an alignment state of the liquid crystal molecules, and the variation of the polarization state effects transmittance variation of light through the LCD, usually due to the use of a polarizer.
An OLED includes two electrodes (e.g., a pixel electrode and a common electrode, similar to the LCD) and an emission layer interposed between the two electrodes, in which electrons injected from one electrode and holes injected from the other electrode combine in the emission layer to generate excitons, and as the excitons discharge energy, the OLED display emits light.
Display devices such as an LCD or OLED further include a switching element connected to a pixel electrode, and a plurality of signal lines such as a gate light and a data line for applying a voltage to the pixel electrode by controlling the switching element.
The constituent elements of the display device are generally formed through a photolithography process. However, as the flat panel display increases in size, the amount of a material, such as a photo-resist, deposited on a substrate to form the constituent elements of the display device in a form of a thin film patterns also increases. Accordingly, manufacturing cost increases, and manufacturing equipment required for a photolithography process becomes larger.
In order to minimize the manufacturing costs and the manufacturing equipment size, an inkjet printing system that forms a thin film pattern by dripping ink has been developed. The inkjet printing system includes an inkjet printing main body and an inkjet head having a plurality of nozzles. In the inkjet printing system, ink is dripped on a substrate through the nozzles of the inkjet head.
In order to discharge a desired amount of ink, a process for measuring and controlling the amount of ink discharged through the nozzles of the inkjet head is required prior to using the inkjet printing system in a manufacturing process.